PROJECT SUMMARY Pediatric obesity is a multifaceted public health concern. Nearly one-third of children with obesity, defined as a body mass index (BMI) ? 95th percentile for age and gender, exhibit cardiometabolic risk factors (CRF), which are associated with accelerated cardiovascular disease, many cancers, and morbidity. Small changes in diet, weight loss, or physical activity can significantly reduce risk for CRF. Although evidence-based interventions delivered by healthcare providers (physicians, nurses, dieticians) exist for the prevention of pediatric obesity for high-risk youth, low participation rates and program availability, as well as nonadherence to recommendations, are significant barriers to positive outcomes. Although they are not widely used, family-centered behavioral interventions are an evidence-based approach that has been found to significantly prevent obesity in children and adolescents. The proposed study uses an adaptation of the Family Check-Up (FCU) to target health behavior (HB) change, termed the FCU-HB program, in youth with elevated BMI. Extensive data support the original FCU's efficacy in improving child outcomes across domains of health and functioning, including the prevention of obesity, through family-level mechanisms of action. The FCU-HB is an assessment-driven approach to tailoring services and increasing motivation to address the behavioral health needs of overweight and obese children and their families. We will conduct a pragmatic randomized trial to test the effects of the FCU-HB program in pediatric primary care with a multiethnic sample of 350 families with children ages 6 to 12 years who are identified as obese (BMI?95th percentile) or overweight (BMI?85th percentile) with risk identified through the electronic health records (EHR). The FCU-HB will be coordinated with care in three primary care clinics: the general pediatrics clinic at Phoenix Children's Hospital and two federally qualified health centers. All three clinics serve predominantly Medicaid patients and a large ethnic minority population of Mexican Americans and American Indians, who face disparities in pediatric obesity, CRF, and access to care when compared with Non-Latino Whites. Consistent with the literature, providers have reported barriers to pediatric obesity treatment with respect to family functioning, motivation, and adherence to recommendations. The FCU- HB was designed to reduce BMI by improving family engagement and behavioral health practices. This trial aims to facilitate sustainability and scale up. Community and scientific boards will provide guidance on study and program design to ensure the program achieves this aim and is found to improve children's weight. We will use a multi-method and multi-informant assessment strategy including EHR data, behavioral observation, questionnaires, and interviews to assess the impact of the FCU-HB on BMI as a primary outcome, child health behaviors, parenting, and service utilization. We will also assess implementation outcomes, including acceptability, adoption, feasibility, appropriateness, fidelity, and cost, which will provide actionable information for sustainable delivery in other healthcare systems.